This application claims the priority of German Patent Document DE 101 33 118.5, filed on Jul. 7, 2001, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a transmission system for a motor vehicle comprising a vehicle transmission equipped for longitudinal installation with a gear output shaft that points in the direction of the rear of the motor vehicle in the installed state.
From U.S. Pat. No. 4,289,213 a transfer case for a motor vehicle is known, which contains a vehicle transmission system equipped for longitudinal installation with a gear output shaft that points in the direction of the rear of the motor vehicle in the installed state. The gear output shaft can be connected and supported for rotation on an input shaft via a transfer case and via a cardan shaft. This cardan shaft is guided laterally along a gear housing of the vehicle transmission system to the front axle gear unit. An intermediate shaft that is connected with the cardan shaft via a cardan joint can swivel to the gear output shaft of the vehicle transmission system.
Furthermore, in particular, transmissions in all-wheel drives are known, which contain an automatic transmission that was originally designed for rear wheel drive and where based on the so-called “add-on principle” an additional drive connection is established with a front axle gear unit via a cardan shaft.
An aspect of the invention is based on making a generic transmission available, which can be integrated into a narrow vehicle tunnel and nevertheless has small deflection angles of the cardan shaft. It is resolved pursuant to certain preferred embodiments of the invention wherein for reducing at least one deflection angle of the cardan shaft, at least one shaft connected to the cardan shaft is swiveled towards the gear output shaft of the vehicle transmission and wherein at least one gear wheel of the lateral drive unit is conical. Further embodiments result from additional features and configurations.
A transmission system for a motor vehicle, which contains a vehicle transmission equipped for longitudinal installation with a gear output shaft that points in the direction of the rear of the motor vehicle in the installed state is provided, wherein the shaft can be connected and be supported for rotation on an input shaft of a front axle gear unit via a driven shaft of a transfer case and via a cardan shaft.
It is suggested that for reducing at least one deflection angle of the cardan shaft at least one shaft corresponding to the cardan shaft be able to swivel to the gear output shaft of the vehicle transmission. A smaller axis distance between the gear output shaft of the vehicle transmission and driven shaft of the transfer case can be made possible despite small deflection angles. The transfer case can have a space saving, lightweight and cost-effective design and the transmission system can be integrated in a narrow vehicle tunnel in particular due to the space-saving transfer case.
The swiveling of the shaft of the transfer case is beneficially accomplished by designing the transfer case as an angular gear with bevel wheels or by designing the transfer case as a wheel chain with at least three gear wheels, wherein at least one gear wheel is conical. A transfer case designed as a wheel chain can take on a particularly space-saving design.
The swiveled shaft, which is in the flow of power between the gear output shaft and the cardan shaft, can be designed as a hollow shaft with external toothing in the extreme case, which holds a joint of the cardan shaft radially inside.
Certain preferred embodiments of the invention can be applied in pure front-wheel drives with manual transmissions and in particular with automatic transmissions. Particularly beneficial however is the application in all-wheel drives, which have a vehicle transmission, especially automatic transmission, that is designed for rear-wheel drive, i.e. where the gear output shaft can be connected and supported for rotation on an input shaft of a rear axle gear unit and the gear output shaft based on the so-called “add-on principle” can be connected and supported for rotation on an input shaft of a front axle gear unit via a cardan shaft. Despite a vehicle transmission that is basically designed for rear-wheel drive, the cardan shaft can be guided with small deflection angles along a housing of the vehicle transmission at a small distance. Shell modifications on a tunnel for all-wheel drive variations of a vehicle equipped basically with purely a rear-wheel drive can be reduced to a minimum or possibly be completely eliminated.
In a beneficial embodiment, either the input shaft of the front axle gear unit corresponding to the cardan shaft and/or the driven shaft of the transfer case corresponding to the cardan shaft can swivel towards the gear output shaft, specifically vertically and/or horizontally. Instead of swiveling the input shaft of the front axle gear unit or the driven shaft of the transfer case it is basically also feasible to provide additional swiveling intermediate shafts.
The input shaft of the front axle gear unit is beneficially swiveled vertically and/or horizontally by an angle between 1° and 10° and the driven shaft of the transfer case is beneficially swiveled vertically and/or horizontally by an angle between 1° and 20°.
In order to swivel the input shaft of the front axle gear unit and/or the driven shaft of the transfer case, all designs that appear reasonable to the expert are feasible.
In particular, however, a swiveled input shaft of the front axle gear unit can be accomplished by either arranging the entire front axle gear unit in a swiveling manner, which allows a less expensive standard front axle gear unit to be used, or by allowing the front axle gear unit to exhibit beneficially an angular gear with an angle not equal to 90°. In the latter case, lateral shafts of the vehicle can take on a standard design.
In another embodiment of the invention, it is suggested to swivel a rotational axis of an intermediate gear wheel of the transfer case design as wheel chain to the gear output shaft, wherein beneficially a favorable swivel angle of the driven shaft of the transfer case, an additional position adjustment as well as beneficial gear ratios can be accomplished in a simple and cost effective manner.
Furthermore, space can be saved by incorporating the transfer case designed as wheel chain in a swiveling manner about a rotational axis, preferably about an angle between 20° and 40°.
When the vehicle transmission system contains a gear housing with a molded-on storage unit for the transfer case, an additional intermediate housing can be avoided between the vehicle transmission and the transfer case, and thus additional components, space, assembly efforts and costs can be saved.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.